1. Technical Field
The present disclosure relates to an image lens system, and more particularly, to an image lens system having multiple lens elements alternating with positive and negative refractive powers.
2. Related Art
In recent years, an optical lens assembly is widely used in various applications, such as mobile phone camera, webcam, car camera, video surveillance system and electronic entertainment device. The photo-sensing device of an ordinary photographing camera is commonly selected from a charge coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS) device. In addition, with the advance of semiconductor manufacturing technology, the miniaturization of pixel size of the photo-sensing device is enabled, which develops the high pixel density and miniaturization of the optical lens assembly. Therefore, how to obtain superior image quality by the miniaturized optical lens assembly of the compact photo-sensing device is the main goal for manufacturers.
Considering the imaging need of capturing a wide range of area at one time, the general optical lens assembly applicable to car, video surveillance system and electronic entertainment device requires a larger field of view. The structure of a front lens group with negative refractive power and a rear lens group with positive refractive power is adopted in a conventional wide-angle photographic lens assembly, constructing a so-called inverse telephoto structure, thereby obtaining the characteristic of wide field of view. For example, U.S. Pat. No. 7,446,955 discloses a four-lens structure having a front lens group with negative refractive power and a rear lens group with positive refractive power. However, such lens assembly structure may obtain larger field of view, but this lens structure with only one lens element in the rear group is unfavorable for minimizing the aberration. Moreover, due to the popularization of a rear view camera in modern automobiles, the adoption of the wide-angle optical lens assembly with high resolution is becoming a trend. In view of this, there is a need that the total length of a wide-viewing-angle optical lens assembly with high image quality is not excessively long.